led indicators

[paulwhalley]

hello im new on here and a complete novice
what i want to do is add some marker lights to my van, orange running down the side of the van.
that's the easy bit for me. they will be wired into the 12v supply to the side light, but what i want them to do is flash in sequence running down the side of the van when indicating. how would i get this to work? i have looked at the arduino uno and can see how to do the coding to get the sequence to work, i may just be over thinking it and getting my self confused!
many thanks
paul

 

[Harald Kapp]

Welcome to electronics point, Paul.

There are a few things to consider:

1. Is it legal to have this kind of lighting on your van where you use it?
2. How many LEDs are you going to use and what tradeoff between wiring, lines of code and cost are you willing to accept?

Let's assume you have cleared #1 - it's entirely your responsibility.

An Arduino or similar is a possible solution. But the Arduino has a limited number of GPIO pins, very likely not enough to drive all your LEDs directly. A possible way ot of this dilemma is by using a serial protocol. Again you have many choices to implement this.
May I suggest you look into addressable RGB LED strips using WS2812B LEDs (Google)?
These strips come in various lengths and various numbers of LEDs per meter. Also available in a waterproof version (probably right for use on your van). They can easily be cut to the desired length. The color and intensity of each single LED can be controlled by a single data line. Libraries are available for the Arduino that hide the complex timing from you. You simply tell the library which LEDs are to be activated in terms of color and brightness. You can easily achieve various effects including but not limited to the flash sequence you're looking for.
See e.g. this reference for a few more details.

Plus you will need a 12 V to 5 V step-down regulator - you will need it anyway for the Arduino, but a beefier version (more amps) to drive the LED strip.
Do not use the ubiquitous 12 V RGB LED strips with separate control of Red, Green and Blue. These cannot be controlled directly by an Arduino and will by no means be able to produce the flash effect you're seeking.

Again: ensure it is legal to use such a contraption where you use your van.

 

[paulwhalley]

thanks for the quick reply!
i don't want to go down the strip led route i an looking at using ( eBay item number 333479320912 ) .
i would be looking to put 8 / 10 on each side. what other solutions would you suggest to the arduino?
reference demonstration the first one is what i want to achieve when the indicator is turned on, when the indicator is of i want them to remain solid.

 

[Harald Kapp]

Without addressable LEDs you will need a means to create more GPIO pins to control every single LED individually. A port expander can be used.
Or limit the number od LEDs to 7 per side, then you can use the 14 digital I/O pins of an Arduino Uno directly.

Note that you will require additional drivers and current limiting resistors for each LED (one per LED) as LEDs cannot be directly connected to an Arduino's (or port extender's) output pins. Got a question about driving LEDs? This ressitor is not required for the WS2812B LED strips.
While a single digital output pin of an Arduino can deliver up to 20 mA, you cannot drive 20 mA through all 14 output pins at the same time (all LEDs on). The max. output current for all digital I/O pins is in total <= 150 mA (reference). That would make for 1 mA per LED, way too little for shining brightly.

Here's an example of a project driving 32 LEDs from an Arduino using a TLC5940 driver.

 

[paulwhalley]

thanks for the info but i think im in way over my head
i will keep looking over what you have said and see if i can get my brain in gear lol
thanks again
paul